This study has addressed itself to the relationship of polyamines to the growth of tumor cells. Abnormal concentrations of polyamines are being shown in brain tumors and subsequently experimentally altered polyamine concentrations in the media of cultures tumor cells can accelerate or retard their growth. C14 putrescine studies are being performed with preliminary results showing that when putrescine is added to the media it does enter the tumor cells. There is a negligible breakdown of putrescine within the cells but there is a considerable breakdown by medium when it contains 10 percent fetal calf serum. Aminoguanidine which inhibits the oxidative deamination of putrescine when added to the medium remains active throughout the test period and accelerates the growth of the tumor cells. Evidence that putrescine uptake and release by the cells is active lends support to the view that there is actual turnover of putrescine. A related study correlating histopathology to polyamine concentrations is continued; it suggests that the ratio of putrescine to spermine or the ratio of putrescine to spermidine is more important than the absolute values in relationship to the degree of malignancy.